Hot-air furnace.



. J. & H. B. FARQUHAR.

HOT AIR FURNAGE.

APPLICATION FILED MAR.15, 1902. BBNBWED APR. 20.1909.

Patented June 1, 1909.

` to `generate rity against the menace MILTON J. FARQUHAR AND HENRY B. FARQUHAR, OF

DIRECT AND MESNE ASSIGNMENTS, TO THE FAR MINGTON, OHIO, A CORPORATION Ol" OHIO.

WILMINGTON, OHIO, AssIeNORs, BY Unia FURNAOE COMPANY, OF WIL- Ho'r-AIR FURNAOE.

Application filed March 15, 1902, Serial No. 98,445. Renewed April 20, 1909.

To all whom it may concern:

Be it known that we, MILTON J. FARQUHAR and HENRY B. FARQUHAR, citizens of the United States, residing at Wilmington, in the County of Clinton and State of Ohio, have invented certain new and useful Improvements in Hot-Air Furnaces, of which the following is a full, clearand exact description, such as will enable others skilled in the art to which the invention appertains to make and usey the saine. y

Our invention relates to heating' furnaces having a fire-box within an air-box orx casing for the heating medium. x

The principal objects ofthe invention are: a maximum amountv of heat from the fuel and eifectivel transfer practically all availablelhet to t e circulating a' currents for distribution tothe rooms; (2) te maintain an economical and lasting fire, and a limited fire, producing heat ample in volume but soA moderate in intensity as to prevent clinker and avoid red 'hot metal or scorched air (3) to effect equaole distribution of heat to the walls of vthe fire-box, avoiding the usual high concentration of heat at the dome and eliminating ineffectual surfaces and dead-air blankets which are commonly the source` of much waste, deterioration and scorching of air and wreckage of the furnace; (4) to obtain absolute and permanent secuof poisoned air by l l leakage of gases through the walls of the firebox, and incidentally against escape of smoke that damages the decorations and furnishings of a home 3 and also to prevent interference with the control and economy of the fire by leakage of an' into lthefire-box. Withthe foregoing and other objects in view, the invention will hereinafter be first fullydescribed by reference to the accompanying drawings, which form apart ofthisl specincation, 'and then more 'particularly pointed out in the apnended'claims.

n'ssaid drawings: igure .1 is a vertical transverse section of a hot-air furnace embodying our invention. Fig. 2 is'avertioal longitudinal section of the same. Fig. 3 is a front perspective vienr ofthe furnace, with a portion of the outer casing or air-,box broken 4 is a detail cross-section of one of the longitudinal Welds of the fire-box..

Specification of Letters Patent.

A wardly and welded together away and showing meinten-ier fire-bex ucts of combustion. 'A As shown in the drawings, the furnace has Patented June 1, 1909. seal No. 491,193'.

' a tubular fire-boxl which consists preferably of a seamless and) j-ointless metal shelLapproximately oval in cross-section and with peaked top and bottom the sides of the firebox consisting of vQppositely curved or bowed steel plates 2, meeting at an angle and welded together along the top and bottom ridges, and'welded also to-a rear head or end plate 1. The meetingl edges 3 may be fianged Outsubstantially as shown 1n Fig. 4. Said fire-box is arranged horizontally in the enveloping air-box or aircasing 24, and projects through the front thereof' and'has an exposed front plate 4. All the doors, dempers, draft-Openings, 'oints (including pipe-connection) and regulating or governing devices are placed on said exposed front of the fire-box. These include the ie-floor,the ash-door 13, and a checkdoor o. valve 14 of a smoke-box 9 which is` constructed on thelbase of said front plate and is in communication with the smokepire..

it'hin the air-casing, the fire-box is or may be a continuous integral metal shell, Without seam, rivet or joint and without opening, valve, damper or pipe-connection, so that there is absolute security against leakage of poisonous gases to contaminate the air of. the dwelling, as well as security against leakage of air into the fire-box to inerfere with the control and economy of lthe re.

The fire-box contains a longitudinal rate and fire-pit 6, having a back bridge-wa l 12, and an ash-pan 5 under the grate, said ashpan being substantially U-shapedin crosssection. These are arranged to leave a back diving flue 7 and a communicating bottom flue 8, the llatter extending to the front smoke-box 9. There is thus provided in the rear and bottom of the nre-box an indirect draft-passage through which .the of combustion pass and have their let at the base of the furnace front, into the'smoke-.box 9 which extends downward andhas an qutlet-openi 1 tothe ch ininey or smoke-pipe. Thlsont desirably -situated below the fire-box, or with its top ap roximately on a level with the'bottom of t e fire-box, so as to draw off only'the coolest lower stratum of the prodfurtlier advantage smoke-outlet at the al outthat is gained by locating-.the

roducts et-opening is y s combustion to settle and the hottest products of combustion to rise and fill the narrow upward extensions of this flue-space, thus crowding thehotter gases against the heating plates 2 which are constantly being swept by a current of the coolest ail-,"extracting and saving the last residue of heat. A slow movement is maintained within this heat extractor, giving the smoke ample time to part with its heat; while against the outer surface of the metal a swift movement of the cold-air absorbs the heat thoroughly. As aforesaid, the outlet to the sxnokeipe is situated so low down that it draws of' only the lowest stratum, which contains only the coolest products of combustion left within the fire-box.

Within the air-casing are shown radiating plates 25, also conforming to the shape of the fire-box and having both surfaces swept by the ascending air-currents which absorb from suchplates the heat 'radiated from the `fire-box.. The conformation of shape makes the two surfaces parallel, so that the heat is radiated from one surface at 'right angles and absorbed at right angles by the opposite surface. By helpmg tof-extract the heat by radiation, these plates 25iincrease the heatsaving power. g y In connection wlth the furnace, we have illustrated an improved automatic heat-governor or regulating apparatus; tol which, however, no claim per se is made h ereinJ since thisl mechanism forms the `jsnbjectmatter of a divisional application for autoT matic furnace regulator, filed by us Janu-l ary30, 1905, Serial No. 243399. Hence a brief reference will be sufficient. This heatgovernor operates upon the ash-door 13 to control the air admitted to the fuel and upon the check-door 14 in the smoke-flue to check the draft when necessary.' 23 denotes a suspended lever which rocks on a fulcruni edge on the front cross-bar 17. T his lever 23 has a link 'connection with the suspended lever 28, which has suitable connections with the', ash-door and check-valve. The lever 28is 1 provided with a weight 15 which is utilized to move the lever in a direction to o )en the ash-door as the temperature of the furnace i is lowered. 'Said lever is moved in the opposite direction, to close vthe ash-door or restrict the opening thereof and open the checkvalve, by the force of expansion of the firebox when heated against an inclosing framework not heated, and which operates on the lever 23. Said frame-work as shown con# sists of a rear cross-piece 16, having pins or projections 26 that bear against the rear wall of the fire-box to receive its .thrust therefrom when expanded by the heat; and longitudinal connectin rods 21 and 22 connected to ofpposite en s of said rear cross-4 pie'ce 16. ne of the rods 22 is connected to the lever 23 a little below its fulcrum;

While the other-'rod 21 is connected to an ad.

justing lever 20 attached to said front crosspiece 17 and engaging a locking rack IQ/the front cross-piece 17 having a graduated arc 18. When the heat of the fire-boxv causes it to expand against the rear cross-piece 16, the rod 22 draws the lever 23 in 'ard with sufficient force to overcome the weight 15. A s )eciic explanation of this mechanism is made in the specification of our aforesaid divisional application Serial No. 243`Z 99.

lVe claim as our invention and desire to secure by Letters Patenti 1. A furnace comprising a casing, and a horizontally-disposed tubular fire-box in closed therein, said firediox having its front exposed or projecting through the casing and provided with all doors and draft openings, the walls of the fire-box within the casing being closed or imperforate, and a longitudinally-disposed grate, subjacent ashan and rearlnidgewall arranged in the fire-(pmx to provide an indirect draft passage for the )roducts of combustion in the rear and ottom of the fire-box,- said passage having its outlet at the lower front of the fire-box.

2. A furnace comprising a casing, and a fire-box inclosed therein having an exposed front, said fire-box being wholly closed except at its said front wall and containing a fire-pot with bottom grate and ash-pan thereunder arranged to provide an indirect smoke-passage in the bottom of the fire-box,' -its said front wall having a fire-door and ashdoor thereunder and a smoke-box under said ash-door for connection with a smoke-stack or pipe, said smoke-passage leadirig t6 and communicating with said smoke-box, and a check-valve in said smoke-box.

3. In a furnace, a horizontally-disposed tubular tire-box of oval form in cross-section and relatively long and narrow, a' longitudinally-disposed fire-pot therein arranged substantially at the longitudinal middle` of the fire-box and occupying the-'f lull width across thereof, said fire-pot includihg a bottom grate and rear bridge-wall arranged to provide a down-draft flue in the back -ol' the fire-box, and an elevated U-shaped ash-pan under the grate, providing in the bottom of the fire-box a passage for the products of combustion under and straddling the sides oll the ash-pan, said bottom passage being in ciimmunication with said back fine and havine a l'ront outlet.

4. A furnace having a horizontallydisposed tubular re-box provided with a front ash-door, grate, ash-pan and rear bridgewall, there being an indirect draft-passage leading' l'rom the fire-space above the grate down behind Jthe bridge-w: ll and l'orvmrd under the ash-pan, and said bridge-wall having a passage therein `l'or admitting an air-blast from the ash-pan aboveI the fuel.

5. A furnace having` a horizontallydis posed tubular {ire-box, a longitndinally-arranged grate therein providing a fire-space, above the grate, and a U-shaped ash-pan depending below the grate and by its contour in conjunction with the interior walls ol' the iire-box formingr a continuoussmokepassage in the bot-om oi' the iire-box and straddling the ash-pan, .said passage having a iront outlet and'communicating only at they baek ol' the iire-box with the 'lire-space above the grate.

6. A furnace comprising a easing and a liorizontally-disposed ytubular iire-box therein olapproximately upright oval or ellip tical form in cross-section, and a longitudinally-arranged grate and subjacent ashpan in said {ire-box partitioning the same transversely, the contour ol' said ash-pan in conjunction with the sides oi' the 'lire-box providing an approximately inverted A-sl1aped indirect draft-passage in the bottom of the fire-box, said draft-passage being in eommunication at the rear of the fire-box with the space above the grate and having a front outlet.

7. ,"1 l'nrnace comprising an air-box, and an inclosed horizontally disposed tubular fire-box occupying nearly the full space of the air-box, said ire-box being approximatel)Y elliptical in cross-section and having oppositelv bowed Side-plates meeting at an angle. or peak at he top and bottoni, and a grate and raised ash-pan thereunder anl ranged within the lire-box so as to provide a passage Al'or the ].\rodnct.-: ol' con'ibustion under and ai the oppositey sides oi' the ash-pan, whereby the side-walls of the fire-box are exposed to heal a bove and below the grate; and the air-box having its side-walls approximately conforming to the shape oi' the {ire-box, means whereby the air is admitted into the air-bex under the {ire-box, and the air-box having,r air-exit openings above the iirebox, lthere being narrow spaces for circulation ol' air between opposite sides 0i' the 'lire-box and the air-box, said spaces being nearly vertical and only slightly eurve'd inwardly toward the top and bottoni of the fire-box, causing the air-currents t0 sweep closely over and take up the heat from the wholeexterior surface of the sides of the {ire-bok.

MlLTON J. FARQUHAR.

v HENRY B. FARQUHAR.

llitnesses: f/ 'FRANCIS FARQUHAR,

CAROLYN MCPHAIL. 

